This invention relates to an end of aisle control system of the type employed by operator controlled materials handling vehicles.
End of aisle control systems are designed to warn an operator or stop a vehicle when the vehicle is about to exit an aisle, that is, the space between storage racks in which the vehicle is operating. In modern warehouses, the aisles are narrow, so narrow that special guidance systems are used to steer the vehicle. One guidance system uses rail on the racks to engage guiding wheels mounted on the sides of the vehicle. Because the aisles are so narrow, the operator's view of an intersecting aisle is limited, especially when operating in the reverse direction. An end of aisle control system is therefore employed to provide the necessary warning to the operator or to slow or stop the vehicle prior to its entering the intersection or exiting an aisle.
Various techniques for providing end of aisle control have been provided, such as the use of reflective tape and floor mounted magnets. Magnets buried in the floor are preferred since they are not as prone to damage or subject to tampering.
One problem noted with prior art systems has been in the abrupt braking often experience by the operator when the end of aisle control system is operational. Braking actions often take place at unexpected times since the operator may be unaware of how close to the aisle's end the vehicle is presently located. Accordingly, there is a need to alert the operator that the end of aisle zone has been entered and to slow the vehicle in an appropriate manner.
Another problem with prior art systems is found when moving from one aisle to another aisle directly across a wide intersection. If the vehicle is forced into a slow mode of travel after leaving an aisle, then the operator is required to continue in that slow mode until another end of aisle magnet is detected, indicating that a new aisle has been entered. It would be desirable to permit the vehicle to resume its normal speed automatically after the operator has exited an aisle a sufficient distance that a clear view of the intersection is possible.